Diseases and other disorders of the heart valves affect the proper flow of blood from the heart. Two categories of heart valve disease are stenosis and incompetence. Stenosis refers to a failure of the valve to open fully, due to stiffened valve tissue. Incompetence refers to valves that cause inefficient blood circulation by permitting backflow of blood in the heart.
Medication may be used to treat some heart valve disorders, but many cases require replacement of the native valve with a prosthetic heart valve. Prosthetic heart valves can be used to replace any of the native heart valves (aortic, mitral, tricuspid or pulmonary), although repair or replacement of the aortic or mitral valves is most common because they reside in the left side of the heart where pressures are the greatest.
Conventional heart valve replacement surgery involves accessing the heart in the patent's thoracic cavity through a longitudinal incision in the chest. For example, a median sternotomy requires cutting through the sternum and forcing the two opposing halves of the rib cage to be spread apart, allowing access to the thoracic cavity and heart within. The patient is then placed on cardiopulmonary bypass support which involves stopping the heart to permit access to the internal chambers. Such open heart surgery is particularly invasive and involves a lengthy and difficult recovery period.
Percutaneous implantation of a prosthetic valve is a preferred procedure because the operation is performed under local anesthesia, may not require cardiopulmonary bypass, and is less traumatic. Various types of prosthetics are adapted for such use. One class employs a stent like outer body and internal valve leaflets attached thereto to provide one way blood flow. These stent structures are radially contracted for delivery to the intended site, and then expanded/deployed to achieve a tubular structure in the annulus. Another more advantageous class is offered by the assignee hereof. US Patent Publication No. 2005/0203614 (hereinafter “the '614 application,” which application is incorporated by reference herein in its entirety) describes a system in which various panels define the implant body carrying valve leaflets. These prosthetic valve structures are delivered in a contracted state and then unfolded and/or unrolled into an expanded state at the treatment location. An example of such a valve is depicted in FIG. 1A. As shown, valve prosthesis 101 is adapted to carry a valve 107 having multiple leaflets 108. The valve support structure 106 includes a plurality of panels 109 that can transition from the state shown to an inverted state as described in the '614 publication.
With either type of structure, a sufficient engagement between patient body tissue and the prosthesis body is desired to secure the position of the implant and form a peripheral seal. However, when implanting the prosthetic device at the site of/within the envelope of the native valve, the condition of the native valve can interfere with fit. Stated otherwise, irregularity in the shape of the implantation site, surface features, texture, and composition pose challenges for developing an implant of a regular size able to accommodate all such variability.
Aspects of the invention optionally address the challenges presented by prosthetic member interface with calcific and/or irregular valve leaflet and annulus geometry. In addition, other advantages of the present invention may be apparent to those with skill in the art upon review of the subject disclosure.